Vibration absorbing throttle lift bar

ABSTRACT

A vibration absorbing throttle valve lift bar arrangement for steam or gas turbines. A plurality of tubular members are nested concentrically one within the other. The assembly is provided with diametrically disposed bushings to slidably receive the lift bar rods and the valve stems. The tubes are dimensioned to have clearance between them. Preferably, a closure cap is sealed to the ends of the outer tube, and the inner tubes have end clearance with the caps.

United States Patent Charles C. Czuszak Greensburg, Pa. 879,473

Nov. 24, 1969 May 25, 1971 Carrier Corporation Syracuse, N.Y.

lnventor Appl. No. Filed Patented Assignee VIBRATION ABSORBING THROTTLE LIFT BAR 2 Claims, 3 Drawing Figs.

U.S. Cl 415/155, 137/628, 248/358 Int. Cl ..F0lb 25/02, FOld 17/12, F03b 1/04 Field of Search 415/119,

[56] References Cited UNITED STATES PATENTS 2,294,127 8/1942 Pentheny 415/155 2,978,223 4/1961 Keeney et al. 415/155 Primary ExaminerCarlton R. Croyle Assistant Examiner-John J. Vrablik AttorneysHarry G. Martin, Jr. and .1. Raymond Curtin ABSTRACT: A vibration absorbing throttle valve lift bar arrangement for steam or gas turbines. A plurality of tubular members are nested concentrically one within the other. The assembly is provided with diametrically disposed bushings to slidably receive the lift bar rods and the valve stems. The tubes are dimensioned to have clearance between them. Preferably, a closure cap is sealed to the ends of the outer tube, and the inner tubes have end clearance with the caps.

PATENTEDMAY25|9H 3580.691

SHEET 1 [1F 2 17 FIG I INVENTOR.

CHARLES C. CZUSZAK ATTORNEY PATENTEUNAYZSIBYI 3580.691

SHEET 2 OF 2 FIG. 5

VENTOR. CHAR c. CZUSZAK 5 W vg mv,

ATTORNEY 1 VIBRATION AB SORBING THROTTLE LIFT BAR BACKGROUND OF THE INVENTION In one throttling arrangement employed in steam turbines,

' the bottom wall of the steam chest is formed with a plurality of passages leading to the steam nozzles or groups thereof. A valve is provided for each passage. The stems of the valves extend through an elongated lift bar whereby upon upward movement of the bar from the bottom wall of the steam chest, the valves are lifted upwardly out of closure engagement with the passages. Usually, the valves are moved toward open position in a predetermined sequence to effect better throttling of the turbine.

The steam passing through the steam chest at high pressure and high velocity and with considerable turbulence imparts vibration of great magnitude in the lift bar and in the valves. Experience has established the fact that this vibration will develop fatigue in the valve stems, causing them to become fractured with the result that the turbine may be extensively damaged.

SUMMARY OF THE INVENTION This invention has as an object a lift bar assembly embodying a structuralarr'angement which functions to absorb vibration, reducing the transmission thereof to the valve stems. Basically, the lift bar of my invention comprises a plurality of tubular members nested one within the other and dimensioned to have clearance between the tubes. Bushings are disposed diametrically of the assembly to receive the bar lifting rods and the valve stems. The ends of the bushings are sealed into the outermost tube and preferably the assembly includes a cap member sealed to each end of the outermost tube. This arrangement prevents the development of corrosion between the tubular members.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view of the valve assembly, the steam chest being shown in section;

FIG. 2 is an enlarged transverse sectional view taken on line 2-2 ofFIG. 1; and

FIG. 3 is an enlarged lengthwise sectional view of the left portion of the structure shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT The steam chest is formed with top and bottom walls 11,12 and is closed at one end by a wall I3. The opposite end of the chest is connected to the steam supply conduit I4.

The bottom wall 12 is formed with a linear series of passages in each of which is positioned a valve seat 17. A valve is associated with each seat and is formed with a vertically disposed stem 23. The valve stems 23 are slidably mounted in a lift bar assembly 25. The assembly 25 is reciprocated vertically by lift rods slidably mounted in the top wall 11 of the steam chest. The upper ends of the rods 30 are operatively connected to operating linkage (not shown) which in turn is usually connected to a governor mechanism.

Each of the valve stems 23 is provided on its upper end with a stop nut 33. When the lift bar assembly 25 is moved upwardly, the nuts 33 are engaged, moving the associated valves 20 upwardly and out of engagement with the seats 17 for the admission of steam or gas from the chest to the nozzles of the turbine. The nuts 33 are adjustable axially on the stems, whereby the stop nuts are engaged in a predetermined sequence as the lift bar assembly is moved upwardly.

This invention has to do with a structural arrangement of the lift bar assembly. Referring to FIGS. 2 and 3, the lift bar consists of a plurality of tubular members arranged and extending in concentric relation. The outer tubular member of this series is indicated at 35, and the innermost member is indicated at 37 (see FIGS. 2 and 3).

These tubular members are dimensioned so that there is a clearance, as indicated at 40, between the tubes when they are telescoped within one another to make the concentric nesting as shown in FIGS. 2 and 3.

The nested arrangement is formed with a series of apertures. These apertures extend diametrically through the assembly for the reception of bushings 43. The ends of the bushings are fixed to the outer tube 35 as by being welded thereto. The inner tubes of the assembly are formed with clearance holes to provide a clearance 47 about the bushings.

Preferably, a cap 50 is mounted at each end of the assembly and is welded to the outer tube 35. The ends of the inner tubes terminate in spaced relation to the caps 50, providing a clearance as at 51, FIG. 3. With this arrangement, the tubes of the assembly, other than the outer tube 35, are free to move individually within rather close limits in respect to each other and in respect to the bushings 43. With this arrangement, the lift bar assembly functions to absorb vibration imparted to it and to dampen such vibration before it is transmitted to the valve stems 23.

Iclaim:

l. A fluid turbine throttle valve lift bar assembly comprising a plurality of tubular members arranged in concentric relation, said tubular members being dimensioned to provide a clearance space between said members, a plurality of lift rod and valve stem-receiving bushings mounted in said assembly, said bushings extending diametrically of said assembly and being disposed in coplanar relation and being spaced-apart in a direction axially of said assembly, the ends of said bushings being fixedly secured to the outermost tubular member, the remainder of said tubular members being formed with apertures dimensioned to have clearance with said bushings.

2 A fluid turbine throttle valve lift bar assembly as set forth in claim I and including a closure cap mounted at each end of said assembly and being fixed in sealing engagement with said outer member, the ends of said inner tubular members terminating in inwardly spaced relation to said cap. 

1. A fluid turbine throttle valve lift bar assembly comprising a plurality of tubular members arranged in concentric relation, said tubular members being dimensioned to provide a clearance space between said members, a plurality of lift rod and valve stem-receiving bushings mounted in said assembly, said bushings extending diametrically of said assembly and being disposed in coplanar relation and being spaced-apart in a direction axially of said assembly, the ends of said bushings being fixedly secured to the outermost tubular member, the remainder of said tubular members being formed with apertures dimensioned to have clearance with said bushings. CM,2Id turbine throttle valve lift bar assembly as set forth in claim 1 and including a closure cap mounted at each end of said assembly and being fixed in sealing engagement with said outer member, the ends of said inner tubular members terminating in inwardly spaced relation to said cap. 